1. Field of the Invention
The invention is directed to a solid electrolyte with ethylene oxide content created using the layer-by-layer assembly process, employing electrostatic, hydrogen-bonding, or other nonspecific interactions.
2. Description of the Prior Art
An ion-conducting medium is required to stoichiometrically balance any electrochemical reaction. Early electrochemistry relied exclusively on liquid electrolytes, but recent applications are more demanding. Solid polymer electrolytes (SPEs) have replaced liquid electrolytes in many high-performance applications such as batteries, including fuel cells, sensors, and electrochromic devices. Compared to liquid electrolytes, SPEs feature easier processing, enhanced chemical compatibility, and better mechanical properties with only a modest conductivity decrease. Research focuses on two SPE types. The first, known as bionic conductors, are polar polymer matrices (e.g. PEO) solvating a lithium salt. The second, known as single-ion conductors, are polyanions from which a small cation dissociates into the polymer matrix. Attempts to improve SPE ion conductivity focus on 1) enhancing ion mobility by increasing matrix plasticity or reducing crystallinity and 2) enhancing ion pair dissociation by increasing matrix polarity.
One method utilized to create materials that has been developed in recent years is the layer-by-layer (LBL) approach pioneered by Decher, G.; Hong, J. D. Makromolekulare Chemie-Macromolecular Symposia 1991, 46, 321-327. In the original approach, substrates were alternately exposed to solutions containing polyelectrolytes of opposite charges. The substrate surface charge was reversed upon each exposure, enabling the controllable deposition of polymer complexes as thin films. The electrostatic LBL technique has been extended to include many charged systems other than polymers Ariga, K.; Lvov, Y.; Onda, M.; Ichinose, I.; Kunitake, T. Chemistry Letters 1997, 125-126 and even other complexation mechanisms such as hydrogen bonding, Rubner, M. F.; Stockton, W. B. Macromolecules 1997, 30, 2717-2725. Film growth modulation has been achieved by changing deposition solution pH or salt content, Decher, G.; Hong, J. D. Berichte Der Bunsen-Gesellschaft-Physical Chemistry Chemical Physics 1991, 95, 1430-1434 and Decher, G.; Hong, J. D.; Schmitt, J. Thin Solid Films 1992, 210, 831-835.